The present invention relates to the laser welding in the field of dental technology, and more particularly, to a combined gas deliuery and suction system in devices for the laser processing of work pieces in the field of dental technology, especially for bonding prosthesis parts. The suction system serves to exhaust and remove the protective inert gas that is necessary for these operations, and for the elimination of the reaction products formed during the processing of the work pieces. In more particular detail, the suction unit operates with a protective inert gas which is supplied and introduced directly via an annular nozzle concentrically surrounding the conical laser focusing unit.
In the last few years, a large amount of bonding work in dental technology and other technical areas has been carried out by means of laser welding. Such laser apparatuses are state of the art and their structure and operation are known in the dental industry.
The processing of work pieces by means of laser beams normally takes place in the presence of a protective or inert gas. This protective gas can, for example, be supplied directly by way of the conical laser focusing unit or by the annular nozzle which concentrically surrounds the conical laser focusing unit. The inert gas performs the task of protecting the work piece against oxidation during laser processing. During processing, mostly gaseous and solid reaction products are formed, which, in part, can be reactive or even toxic, and therefore must be purposefully removed with the protective gas. These are matters well understood in the art.
In German OLS No. 3,800,050, the tool is surrounded by an annular suction channel for the removal of powdery processing waste. The suction channel, in turn, is surrounded by an annular nozzle which functions to blow compressed air in a vertical direction to the work piece, so that a gas curtain is produced, which is intended to prevent the exiting of the processing waste. In this way, one can eliminate powdery processing wastes but not, however, the supplied protective gas and the gaseous and vaporous reaction products formed during laser processing, since turbulence occurs in the suction channel, which could lead to a possible condensation of the reaction products.
German Patent No. 3,923,829 describes a suction system for the removal of the reaction products formed during the processing of work pieces by means of laser beams. The suction system consists of a laser focusing unit, within which a protective gas can be supplied. A suction hood with several openings, by means of which the reaction products can be suctioned off, is affixed in a gas-tight manner to the conically tapered end of the focusing unit. However, even here turbulence arising in the conduction of the gas cannot be avoided. Furthermore, this system is designed for processing planar work pieces. Its configuration precludes the processing of small work piece components such as those necessary in dental technology, especially manipulations in the laser processing field.
In DE 2,950,457 there is described a laser processing device, in the conical focusing unit of which air or gas is blown in tangentially. In that way, a twist is imparted to the gaseous stream, so that it passes through this unit in the manner of a tornado. The gas is then exhausted through an annular nozzle concentrically surrounding the focusing unit. This construction has the exclusive function of protecting the laser lens from contamination. The turbulent flow unavoidably generated in the area of the focused laser beam is not capable of protecting the work pieces from oxidation, even in the case of using an inert gas.
It is therefore an object of the present invention to develop a suction system in devices for the laser processing of work pieces in dental technology, for the removal of the protective gas employed in such processing, and for the elimination of reaction products formed during the processing of the work pieces which avoids the turbulence problems in prior known devices.
It is a further object of the present invention to develop a system for laser processing in dental technology which operates by supplying a protective gas by means of an annular nozzle concentrically surrounding the conical laser focusing unit and wherein the suctioning of gas and reaction products should take place in a laminar gas flow condition without disturbing components in the work area.